The proposed project studies the etiology, course, and consequences of substance use and substance disorders from a developmental perspective in a high risk sample. In so doing, it addresses a centrally importani question in substance use research-namely, what are the etiological pathways by which risk is transmitted across multiple generations? We predict heterogeneity in trajectories of substance use outcomes among children o alcoholics and controls, identify mediating mechanisms underlying familial alcoholism risk, andexamine emergin, risk in the next generation using a multi-method prospective study. To achieve these aims, we capitalize on a unique multigenerational high risk samplethat spans the ages from 'substance use initiation to the developmentof substance use disorders and adult "maturing out," and for whomdata (have already been collected from three generations (G1-G3). The sample includes alcoholicmothers and fathers whose alcoholism and otherdisorderswere directly ascertained. Beginning in adolescence(M=12.7 years), G2s and) their parents had 3 annual assessments.Further follow-ups (addingfull biologicalsiblings andpeerinformants) were) !done in late adolescence (Wave 4) and early adulthood (Wave 5). Wave 5 also added a baseline multimethodj [assessment of the G3 children (mean age=7.4). At the proposed follow-up, computer-assisted interviews will be conducted with G2adults, their G3adolescent] children, and the G3 adolescent's otherparent. Otherinformant data (peers for adults andteachers for adolescents) (along with school records data will be collected by mail. G3 adolescents will also perform standardized tasks assessing executive and motivational regulatory processes. A short-term 18-month longitudinal design allow; respective prediction of G3 adolescent substance use from existing baseline data as well as the newly.proposed assessments. The findings are particularly important for prevention because they focus on a high risk group,they track the natural history of substance use from its precursors to clinically important end points, they include 'Otentially modifiable factors, and they examine the transmission of risk across three generations.